Brightener compositions

ABSTRACT

HYDROPHILIC COLLOIDS HAVING INTIMATELY DISPERSED THEREIN AN ESSENTIALLY HYDROPHOBIC SOLID SOLUTION OF AN OIL-SOLUBLE BRIGHTENING AGENT IN AN ESSENTIALLY HYDROPHOBIC ORGANIC SOLVENT THAT IS RIGID (AN ORGANIC GLASS) AT ROOM TEMPERATURE, I.E., HAS A GLASS TRANSITION TEMPERATURE (TG) THAT IS ABOVE ABOUT 25*C. AND IS A POLYMER THAT IS AN ACETAL CONDENSATION PRODUCT OF POLYVINYL ALCOHOL AND AN ALDEHYDE OR KETONE HAVING FROM 2 TO 40 CARBON ATOMS ARE ADVANTAGEOUSLY USED IN PHOTOGRAPHIC ELEMENTS AND IN IMAGE RECEIVING ELEMENTS FOR IMAGE DIFFUSION TRANSFER BECAUSE THE LIGHT-STABILITY OF THE BRIGHTENING AGENTS IN THESE DISPERSIONS IS INCREASED SUBSTANTIALLY OVER THE LIGHTSTABILITY OF THE SAME BRIGHTENING AGENTS IN DISPERSIONS OUTSIDE THE IMMEDIATE INVENTION.

United States Patent 3,684,729 BRIGHTENER COMPOSITIONS Robert J. Tuite,Kodak Park, Rochester, N.Y. 14650 No Drawing. Filed Oct. 2, 1969, Ser.No. 863,364 Int. Cl. C09k 1/02; G03c 1/92 US. Cl. 252-3012 W 6 ClaimsABSTRACT OF THE DISCLOSURE Hydrophilic colloids having intimatelydispersed therein an essentially hydrophobic solid solution of anoil-soluble brightening agent in an essentially hydrophobic organicsolvent that is rigid (an organic glass) at room temperature, i.e., hasa glass transition temperature (Tg) that is above about 25 C. and is apolymer that is an acetal condensation product of polyvinyl alcohol andan aldehyde or ketone having from 2 to 40 carbon atoms areadvantageously used in photographic elements and in image receivingelements for image diffusion transfer because the light-stability of thebrightening agents in these dispersions is increased substantially overthe lightstability of the same brightening agents in dispersions outsidethe immediate invention.

This invention relates to brightening compositions having greatlyimproved stability, a method for improving the stability of brighteners,and photographic materials containing brightener compositions havingimproved stability.

The highlight areas of photographic color prints and other products,such as, fibrous or plastic articles are often made to look whiter byincorporating optical brightening agents. These brightening agentsfluoresce under radiation with ultraviolet light, emitting visiblelight, usually bluish in hue thus enhancing the whiteness of the object.Such products also frequently contain ultraviolet sensitive ingredientssuch as dyes, organic polymers, etc., which require protection fromirradiation in the ultraviolet region, especially from 360-400 mBrighteners are inherently ultraviolet absorbers and depend on thischaracteristic for the energy required to fluoresce in the visibleregion of the spectrum. Most of the known brightening agents aredecomposed by prolonged exposure to ultraviolet radiation, and thus losetheir ability to fluoresce and serve as brightening agents, oil-solublebrightening agents, such as a brightener based on vinylene, a conmarin,a thiophene, a furan, an anthracene, a pyrazoline, a fluorene, acarbazole, a 1,8-naphthalic acid imide and a2-oxo-2,4-dihydrofuro[2,3-b] quinoxaline, are well known brighteningagents and are brighteners which absorb and lluoresce in desirableregions of the spectrum. These brightening agents, however, do not havethe desired stability to prolonged exposure to radiation.

It is known to use high boiling solvents, such as, benzyl alcohol,diethyl esters of phthalic acid, etc., which are wholly or partlyreplaced by resins such as polystyrene, polyvinyl acetate, and an esterof polyacrylic acid, to dissolve brighteners such as stilbene fordispersing in aqueous gelatin solution before coating photographicelements. Such methods are described in German Pat. 1,150,274. However,brightening compositions made by these methods either have low[fluorescence or do not have the desired stability to prolonged exposureto light.

It is therefore an object of my invention to provide novel brightenercompositions which have substantially improved stability to prolongedexposure to light.

It is another object of my invention to provide a method for making mynovel brightener compositions which have greatly improved stability toprolonged exposure to light.

Another object of my invention is to provide novel photographic elementsand image-receiving elements which contain my novel brightenercompositions.

These and still other objects will become apparent from a considerationof the following specifications and claims.

These and other objects are accomplished according to my invention bythe preparation and use of my novel brightener compositions inphotographic elements and in image-receiving elements. My brightenercompositions comprise hydrophilic colloids having intimately dispersedtherein an essentially hydrophobic solid solution of an oilsolublebrightening agent in an essentially hydrophobic organic solvent that isrigid (an organic glass) at room temperature, i.e., has a glasstransition temperature (Tg) above about 25 C. and are polymerscontaining recurring units of vinylacetals, i.e., polymers that areacetal condensation products of polyvinyl alcohol and an aldehyde orketone having from 2 to 40 carbon atoms. In my brightener compositions,substantially all of the brightening agent is dissolved in the rigidsolvent. My brightening compositions are valuable because they haveunexpectedly good stability to prolonged exposure to ultravioletradiation. My brightening compositions are advantageously made bydissolving any oil-soluble brightening agent in a rigid organicpermanent polymeric solvent containing recurring units of vinylacetals,and. a temporary liquid solvent and then dispersing the resultinghydrophobic liquid solution into an aqueous hydrophilic colloidsolution. The temporary solvent is then removed by evaporation orwashing, leaving the dispersion of particles of the solid solution of mybrightening agent in the permanent, n'gid, polymeric solvent so theparticles have average diameters that are very small, usually less than.4 micron and preferably less than .1 micron. It is important that mybrightener solution particles be dispersed in an aqueous hydrophiliccolloid binder.

Oil-soluble brightening agents used to advantage in my brighteningcompositions include vinylene brighteners, coumarins, thiophenes (e.g.,thiophenes, dibenzthiophenes, 1,l-dioxydibenzthiophenes, etc.), furans(e.g., furans, dibenzfurans, etc.), anthracenes, pyrazolines, fluorenes,carbazoles, 1,8-naphthalic acid imides, 2-oxo-2,4-dihydrofuro [2,3-b]quinoxalines, etc.

Included among the oil-soluble vinylene brightening agents used toadvantage are the diheterocyclic substituted vinylenes, thediheterocyclic substituted styrenes and the heterocyclic substitutedstilbenes described by the formula:

N N u-l wherein T represents a bivalent vinylene group (e.g., vinylene,a styrene group, a stilbene group, etc.) G and G each represent a membersuch as C, CNH or N; X and X each represent a member such as O, S andNR, N and CR; such that when G and G each represent C, then X and X eachrepresent a member such as O, S and NR, and such that when G and G eachrepresent N, then X and X each represent a member such as N and CR; Rrepresents a member, such as, hydrogen, an alkyl group having from 1 to22 carbon atoms (e.g., methyl, ethyl, benzyl, phenethyl, decyl, dodecyl,docosyl, etc.) and an aryl group, preferably a phenyl group (e.g.,phenyl, tolyl, chlorophenyl, ethylphenyl, bromophenyl, etc.); M and Meach represent the nonmetallic atoms required to complete a 5 to 6membered heterocyclic ring, such as, an oxazole group, a benzozazolegroup, a naphthoxazole group, a thiazole group, a benzothiazole group, anaphthathiazole wherein n represents an integer of from 1 to 2; m and peach represent an integer of from 1 to 2, such that when n is 1, p is 2;J represents a group such as a N group, or a group, a

R group, etc.; R represents a member such as an amino, a halogen (e.g.,chlorine, bromine, etc.), an alkyl group, particularly alkyl having from1 to 15 carbon atoms (e.g. methyl, benzyl, phenylethyl, butyl,cyclohexyl, decyl, pentadecyl, etc.), an aryl group (e.g., phenyl,tolyl, ethylphenyl, ethoxyphenyl, etc.), an alkoxy group (e.g., methoxy,butoxy, pentadecyloxy, etc.), an aryloxy group (e.g., phenoxy, tolyoxy,etc.), etc.; G, G, G X and X are as defined previously; R R R R R R Rand R each represents any monovalent substituent which does not destroythe desirable fluorescent properties of the vinylene brightenersincluding such members as hydrogen, a halogen atom (e.g., chlorine,bromine, fluorine and iodine atoms), hydroxyl, an acyl group (e.g.,acetyl, butyryl, dodecoyl, benzoyl, etc.), an acyloxy group (e.g.,acetoxy, butyryloxy, dodecoyloxy, benzoyloxy, etc.), an amino group(e.g., amino, ethylamino, diethylamino, hydroxyethylarnino,methoxyethylamino, benzylamino, cyclohexyamino, phenylamino,octadecylamino, docosylamino, etc.), a sulfonyl group, such as analkylsulfonyl group (e.g., methylsulfonyl, benzylsulfonyl,dodecylsulfonyl, docosylsulfonyl, etc.), an arylsulfonyl group, such as,a phenylsulfonyl group (e.g., phenylsulfonyl, tolysulfonyl,ethoxyphenylsulfonyl, chlorophenylsulfonyl, etc.), a naphthylsulfonyl(e.g., a-naphthylsulfonyl, [3- naphthylsulfonyl, etc.), a sulfamyl group(e.g., sulfamyl, N-methylsulfamyl, N,N-dimethylsulfamyl,N-docosylsulfamyl, N-benzylsulfamyl, N-phenylsulfamyl, N-tolylsulfamyl,N-chlorophenylsulfamyl, etc.), cyano, thiocyano, thiol, a carbamyl group(e.g., carbamyl, N-methylcarbamyl, N,N-dimethylcarbamyl,N-benzylcarbamyl, N-

docosylcarbamyl, N-tolylcarbamyl, N-(chlorophenyl)carbamyl,N-(a-naphthyhcarbamyl, etc.), a carbamyloxy group (e.g., carbamoyloxy,methylcarbamoyloxy, butylcarbamoyloxy, phenylcarbamoyloxy,u-naphthylcarbamoyloxy, etc.), an alkyl group having from 1 to 22 carbonatoms, e.g., methyl, benzyl, ethyl, phenethyl, ethylphenethyl,isopropyl, butyl, t-butyl, 2,2-diflu0roethyl, 4,4-difluoro-n-butyl,2,2,2-trifiuoroethyl, 6,6,6-trifluoro-n-hexyl, hexyl, cyclohexyl, octyl,decyl, octadecyl, docosyl, etc.), an alkoxy group having from 1 to 22carbon atoms (e.g., methoxy, ethoxy, phenethoxy, butoxy, decyloxy,pentadecyloxy, oetadecyloxy, docosyloxy, etc.), an aryl group, such as,a phenyl group, (e.g., phenyl, tolyl, ethylphenyl, chlorophenyl,bromophenyl, methoxyphenyl, ethoxyphenyl, etc.), a naphthyl group (e.g.,tat-naphthyl, fi-naphthyl, etc.), an aryloxy group, such as, a phenoxygroup (e.g., phenoxy, tolyoxy, chlorophenoxy, hydrophenoxy, etc.), anaphthyloxy group (e.g., a-naphthoxy, fi-naphthoxy, etc.), a furylgroup, a thienyl group, a

NHSO Q group, a

Q L L o t --N\ group, a-N\ group, aN group, a- 0 Q group L L SOzQ,

group; Q and Q each represent a hydrogen atom, an alkyl group (e.g.,methyl, ethyl, butyl, decyl, cyclobutyl, cyclohexyl, methoxyethyl,chloroethyl, etc.), an aryl group, preferably a phenyl group (e.g.,phenyl, tolyl, ethylphenyl, methoxyphenyl, ethoxyphenyl, chlorophenyl,bromophenyl, etc.); Q represents an alkyl group or an aryl group, eachas described for Q; L represents an acyl group (e.g., acetyl, butyryl,dodecoyl, benzoyl, etc.), a ureido group, a AO Q group and a group; Qand Q, are as defined previously; R and R can be any monovalentsubstituent that does not destroy the desirable fluorescent propertiesof the stilbene compound, including hydrogen, alkyl having from 1 to 15carbon atoms (e.g., methyl, ethyl, butyl, 2-ethylhexyl, pentadecyl,etc.), an aryl group, preferably a phenyl group (e.g., phenyl, tolyl,methoxyphenyl, chlorophenyl, bromophenyl, etc.); Z Z Z and Z eachrepresent a member, such as, hydrogen, an alkyl group having from 1 to22 carbon atoms as defined previously for R an aryl group including aphenyl group as defined previously for R and a naphthyl group aspreviously defined for R and Z taken together with Z and Z takentogether with 2,, represent the nonmetallic atoms required to completerings represented by the formulas I'm 1'11: l: 12 R13 ra- R14 I 1 14 RmR10 (8 7 4,4 -bis -trifiuoromethy1benzoxazol-Z-yl) -2- cyanostilbene 88) 4,4'-bis (5-carbornethoxybenzoxazol-Z-yl) -2-cyanostilbene (89)4,4'-bis S-acetamidobenzoxazol-Z-yl -2-cyanostilbene 90) 4,4-bisS-cyanobenzoxazol-Z-yl -2-cyanostilbene (91) 4,4-bis[4,6-dichloro-s-triazinyl (2 amino] stilbene (92)4,4bis(6-phenoxybenzoxazol-2-yl)-a-cyanostilbene ('93)4,4'-bis(6-'[p-methoxyphenoxy]benzoxazol-Z-yl)- a-cyanostilbene 94)4,4-bis 6-carbomethoxybenzoxazo1-2-yl) -a-cyanostilbene (95) 4,4-bis[4,6-diphenoxy-s-triazinyl (2 amino] stilbene (96) 4,4'-bisS-ethoxybenzoxazol-Z-yl) -a-cyano-2- methyl-3 -chlorostilbene (97)4,4'-bis [4,6-dimethoxy-s-triazinyl (2 amino] stilbene Coumarinbrightening agents used to advantage include those in the formula:

(III) D1 CD Dz l wherein D and D each represent a member, such as,hydrogen, an alkyl group (e.g., methyl, benzyl, propyl, amyl, octadecyl,docosyl, etc.), an aryl group, particularly a phenyl group (e.g.,phenyl, tolyl, ethyl phenyl, triazinylaminophenyl, etc.); D and D eachrepresent a member, such as, hydrogen, an alkyl group (e.g., methyl,phenethyl, amyl octadecyl, etc.), an alkoxy group (e.g., methoxy,ethoxy, amyloxy, pentadecyloxy, etc.), an aryl group (e.g., phenyl,tolyl, methoxyphenyl, u-naphthyl, B-naphthyl, etc., an aryloxy group(e.g., phenoxy, tolyloxy, etc.), an amino group (e.g., amino,dimethylamino, butylamino, anilino, diphenylamino, triazinylamino,4,6-dichloro-s-triazinylamino, 4,6 dimethyl-s-triazinylamino, 4,6diphenoxy-s-triazinylamino, ureido, 2-dirnethylaminoethyluredio, etc.),a heterocyclic group (e.g., a pyrazolyl group, a triazol-Z-yl group,such as triazol-Z-yl, benzotriazol-Z-yl, [4,5-a] naphthotriazol 2 yl,[4,5-b]naphthotriazol-Z-yl, etc.), and taken together D and D representthe nonmetallic atoms required to complete a benzene ring.

Typical coumarins used to advantage include the following:7-diethylamino-4-methylcoumarin 3-ethoxycarbonylbenzo (f) coumarin3-phenyl-7- [2- dimethylaminoethyl ureido] coumarin4,6-dimethyl-7-methylaminocoumarin 3-phenyl-7-ureido coumarin3-pheny1-7- [4,6-dichloro-s-triazinyl- (2' amino] coumarin3-phenyl-7-[4,6'-dimethoxy-s-triazinyl(2')arnino1- coumarin 3-phenyl-7-[4'6-'-dimethylmercapto-s-triazinyl (2' amino] -coumarin 3 -phe nyl-7-[4, 6'-diphenylmercapto-s-triaziny1(2') amino] -coumarin 3 -phenyl-7-[4, 6- diphenoxy-s-triazinyl- (2') amino] coumarin3-phenyl-7-[4'-methoxy-6'-methylmercapto-s-triazinyl- (2 amino]-coumarin 3 -pheny1-7- [4'-methoxy-6'-phenylmercapto-s-triazinyl-(2')amino]-coumarin 3-phenyl-7-[4-methoxy-6'-phenoxymercapto-s-triazinyl- 2' amino] -coumarin3-phenyl-7- [4'-chloro-6'-diethylamino-s-triazinyl- ('2')aminol-coumarin 3-phenyl-7-[4',6-dichloro-s-triazinyl-(2')ureido]-coumarin 3-phenyl-7-( [4,5-a] naphthotriazol-Z-yl)-coumarin3-methy1-7-pyrazolyl coumarin Oil-soluble thiophene, furan, thiazole andoxazole brightening agents used to advantage are included in theformula:

wherein X, X, Z Z Z 2,, G and G are as defined previously; X represents0, S, NR; X represents N or CR R and R each represent a member, such as,hydrogen, an alkyl group, preferably having from 1 to 15 0 carbon atoms(e.g., methyl, ethyl, benzyl, butyl, amyl,

decyl, pentadecyl, etc.), an aryl group (e.g., phenyl, tolyl,ethoxyphenyl, etc.), a heterocyclic group, e.g., a Z

group, etc.; and oil-soluble dibenzthiophene, 1,1-dioxydibenzthiophene,dibenzfuran, fluorene and carbazole brightening agents usedadvantageously are included in the formula:

wherein R and R represent a member, such as, hydrogen, an alkyl group,preferably having from 1 to 15 carbon atoms (e.g., methyl, benzyl,propyl, amyl, decyl, pentadecyl, etc.), an aryl group (e.g., phenyl,tolyl, ethoxyphenyl, etc.), etc.; X represents a member, such as, S0 CH2Oil-soluble anthracene brightening agents used to advantage are includedin the formula:

(VI) Il a wherein R and R are as defined previously; and R and Rrepresent a member such as hydrogen, an aryl group 9 (e.g., a phenylgroup, such as, phenyl, tolyl, ethylphenyl, etc. and naphthyl) and thecyano group, such that no more than one of R and R is hydrogen.

Typical examples of anthracene brightening agents include:

9-cyanoanthracene 9, IO-dicyanoanthracene 9-cyano-10-phenylanthracene9,10-diphenylanthracene 9-naphthylanthracene 1O Oil-soluble pyrazolinebrightening agents used to advantage include those of the formula:

Q GEM-N- wherein R represents a group, such as, a carboxylic acid alkylester (e.g., methoxycarbonyl, a sulfonic acid amide group, etc.),hydrogen, an alkyl group, an aryl group, etc., and R representshydrogen, a halogen atom, an alkyl group (e.g., methyl, ethyl, amyl,pentadecyl, etc.), an aryl group (e.g., phenyl, tolyl, etc.). Typicalexamples include the following:

1 (4 methylcarbonyloxyphenyl)-3-pentadecylphenylpyrazoline 3-chlorophenyl-1- (4-methylcab onyloxyphenyl) pyrazoline Oil-soluble1,8-naphthalic acid imide brightening agents used to advantage arerepresented by the formula:

(VIII) R 111 o=o 0=o I RrK/GR IIKPRM wherein R and R are as defined incol. 3, R and R represent hydrogen, an alkyl group (e.g., methyl, ethyl,benzyl, amyl, decyl, etc.) and an aryl group such as a phenyl group,(e.g., phenyl, tolyl, ethylphenyl, etc.); and O X represents 0, S, NH--,NR, NHCO-, a bond, etc. wherein R is as defined in col. 2. Illustrativeexamples include:

4-ethoxy-N-methyl'1,8-naphthalene dicarboxylic acid imide 4-dipentylamino-N-phenyl-6-methyll, S-naphthalene dicarboxylic acid imide4-ethylthio-N-phenyl-1,S-naphthalene dicarboxylic acid imide wherein Ris as defined above; R and R each represent a member such as hydrogen,alkyl, and aryl as defined previously under Formula V. Typical examplesinclude the following:

10 4-methyl-3-phenyl-2-oxo-2,4-dihydrofuro[2,3-b] quinoxaline3,4-diphenyl-2-oxo-2,4-dihydrofuro[2,3-b] quinoxaline 4,6-diethyl-3-pheny1-2-0X0-2,4-dihydrofur0 [2,3-b]

quinoxaline Essentially hydrophobic rigid organic solvents having aglass transition temperature, i.e., Tg, above about 25 C. used toadvantage according to my invention are preferably photographicallyinert, i.e., do not change the sensitivity or developability of silverhalide emulsions; they are compatible with the photographic processingsolutions, are preferably colorless, transparent or translucent and havea refractive index that is in the same general range as the refractiveindex of the hydrophilic colloid that it is to be dispersed in. My rigidsolvents are non-diffusible in the hydrophilic colloid layers containingthem. My rigid solvents include polymers (i.e., copolymers, terpolymers,etc.), mixtures of polymers, etc. such that the solvent has a Tg aboveabout 25 C. (ambient room temperature) and preferably above 40 C. When aphysical mixture of compounds (as opposed to, for example, a copolymer)is used as my solvent, it is not the Tg of the individual componentsthat is important, but the Tg of the composite mixture.

The glass transition temperature range is the range of temperatures overwhich the specific heat and thermal coeflicient of an amorphous materialundergoes discontinuities and is such that below this temperature rangethe material is glass-like in character and that above this temperaturerange, the material is fluid-like. The glass transition temperature, Tg,is the temperature coordinate of the upper asymptote of a graph ofspecific heat vs. temperature or thermal coeflicient vs. temperature andis the temperature at which a glass-like material becomes completelyrubbery or fluid-like.

Rigid solvents used advantageously include polymers having recurringunits of the formula:

wherein E and E each represent a member such as hydrogen and a methylgroup such that not more than of E and B are methyl; E and E eachrepresent a member such as hydrogen, an alkyl group, preferably alkylhaving from 1 to 20 carbon atoms (e.g., methyl, ethyl, benzyl,phenethyl, amyl, decyl, pentadecyl, octadecyl, docosyl, etc.), and anaryl group such as a phenyl group (e.g., phenyl, tolyl, ethylphenyl,chlorophenyl, fluorophenyl, etc.) and a naphthyl group (e.g.,or-naphthyl, B-naphthyl, etc.) such that not more than one of E and E ishydrogen. 7

My polymeric solvents include those having recurring units of:

wherein E, E E and E are as defined previously; x is a number from about.4 to 1.0, preferably from .6 to .9; E represents a member such ashydrogen and an alkyl group having from 1 to 20 carbon atoms (e.g.,methyl, ethyl, benzyl, hydroxyethyl, arninoethyl, carboxyethyl,phenethyl, methoxyethyl, amyl, decyl, octadecyl, etc.); and a COE group;and E represents an alkyl group as described for E and an aryl group(e.g., phenyl, tolyl, carboxyphenyl, aminophenyl, 4-methoxyphenyl,a-naphthyl, fi-naphthyl, etc.).

11 My polymers are advantageously prepared by polymerizing CH2CE COEunits, alone or with other vinyl polymers, then hydrolyzing to convertthe OCOE groups in the polymer to OH groups (usually leaving from about1% to about 3% of the OCOE groups on the polymer), then condensing thehydrolyzed polymer with a compound having the formula /C=O E1 Thepolymers in which up to 50% of E and E represent methyl groups areadvantageously prepared by polymerizing vinylacetate units with up to anequimolar amount of isopropenyl acetate (i.e., a-methyl vinyl acetate)units followed by the hydrolysis step and subsequently by condensationwith the appropriate aldehyde or ketone.

- Typical polymeric solvents used to advantage in my brighteningcompositions include the following:

(1) copoly(vinylacetal) (vinyl Z-carboxybenzoate) (vinyl alcohol) (vinylacetate) 80: :3 :2 by weight (2) copoly(vinylacetal) (vinyl2-carboxybenzoate) (vinyl alcohol) (vinyl acetate) 90:5 :3:2 by weight(3) copoly(vinylacetal) (vinyl Z-carboxybenzoate) (vinyl alcohol) (vinylacetate) 70:20:8:2 by weight (4) copoly (vinyl butyral) (vinyl alcohol)(vinyl acetate) 88:9:3, by weight, m. wt. 34-38,000

(5) copoly (vinyl butyral) (vinyl alcohol) (vinyl acetate) 88:9:3, byweight, 111. wt. 4555,000

(6) copoly(vinyl butyral) (vinyl alcohol) (vinyl acetate) 80:17:3', byweight, m. wt. 24-28,000

(7) copoly(vinyl butyral) (vinyl alcohol) (vinyl acetate) 80: 17:3, byweight, m. wt. 30-34,000

(8) copoly (vinyl butyral) (vinyl alcohol) (vinyl acetate) 80:17:3, byweight, In. wt. 5560,000

(9) copoly(vinyl butyral) (vinyl alcohol) (vinyl acetate) 80:19: 1, byWeight, 111. wt. 3845,000l

(10) copoly(6-methylene-2-phenyl-1,3-dioxalane) (vinyl alcohol) (vinylacetate) 80: 17:3 by weight (11copoly(6-methylene-2-a-naphthyl-1,3-dioxalane) (vinyl alcohol) (vinylacetate) 80: 17:3, by weight (12)copoly(6-methylene-2-methyl-2-propyl-l,3-dioxalane) (vinyl alcohol)(vinyl acetate) 88:9:3, by weight (13)copoly(6-methylene-2-octadecyl-1,3-dioxalane) (vinyl alcohol) (vinylacetate) 88:9:3, by weight (14)copoly(6-methylene-2,4-dimethyl-1,3-dioxalane) (vinyl alcohol)(oz-methyl vinyl alcohol) (vinyl acetate) (ct-methyl vinyl acetate)80:7:7z3 3, by weight The above and other rigid, organic, essentiallyhydrophobic solvents of my invention are used alone or in mixtures asthe permanent solvent for dispersing my brightening agents providing thesolvent has a Tg above about 25 C. The solvents listed above can be usedin mixture with an essentially hydrophobic organic material that has aTg less than 25 provided the mixture has a Tg above about 25 C. The Tgsof mixtures can be estimated to a fair degree of accuracy by linearinterpolation between the Tgs of the components.

It is advantageous to use a temporary solvent in the preparation of mybrightening agent dispersions. Any of the photographically inert, lowboiling organic solvents for the brightening agents and rigid permanentsolvent are used to advantage, including for example, nitromethane,nitroethane, methyl acetate, ethyl acetate, propyl acetate, butylacetate, ethyl formate, butyl formate, etc. Enough temporary solvent isused to make a liquid solution of the brightener and permanent solventwhich is easily dispersed by conventional means into aqueous hydrophiliccolloid. The temporary solvent is removed from the dispersion by 12evaporation and/or by washing, leaving a dispersion of a rigid solutionof the brightening agent in the permanent solvent. Usually it isadvantageous to prepare the disper sion so that the average diameter ofthe particles of rigid brightener solution in the permanent solvent isless than .4 micron. Very good dispersions have rigid brightenersolution particles with an average diameter in the range from about .1to about .2 micron and the preferred dispersions have rigid solutionparticles with an average diameter of less than 0.1 micron.

The ratio of brightening agent to permanent rigid solvent is usually inthe range from about 1:1 to about 1: 1000 parts by weight. A preferredratio is in the range from about 1:10 to about 1:100. The optimum ratiowill de pend upon the particular materials being used and the resultsdesired, and can be determined by methods Well known in the art.

It is important that my hydrophobic brightener solution particles bedispersed in a hydrophilic colloid so that the material can be coatedfrom an aqueous composition, and so that there are no adhesion problemsat the interface between the brightener layer and contiguous layers suchas support, baryta layer, photographic emulsion layer, etc.

Any of the well known hydrophilic colloids used in photographic elementsare uesd to advantage, including gelatin, albumin, collodion, gumarabic, agar-agar, cellulose derivatives, such as, alkyl esters ofcarboxylated cellulose, hydroxyethyl cellulose, carboxymethylhydroxyethyl cellulose, synthetic resins, such as the amphoteric copolymers described by Clavier et al. in US. Pat. 2,949,442, polyvinylalcohol, polyvinyl pyrrolidone, and others well known in the art.

Any of the conventional photographic support materials are usedadvantageously for making my photographic elements, includingphotographic paper support, paper coated with a reflection pigment,e.g., baryta (i.e., barium sulfate), titanium dioxide, zinc oxide, etc.,paper or other fibrous material coated with a hydrophobic resin [e.g.,poly(ethylene terephthalate), polyethylene, polypropylene,poly-(3-methylbutene-1), poly(octene-l), poly(decene-l), polyamides,polyacetals, polycarbonate cellulose triacetate, cellulose acetatebutyrate, ethyl cellulose, etc.] which are advantageously treated withcorona discharge techniques just prior to coating the first gelatinlayer over the resin as described in US. patents, such as 3,220,842,2,864,755, 2,864,756, etc., glass, conventional photographic filmSupports such as cellulose acetate cellulose nitrate etc., metal, etc.Baryta is coated in the range from about .9 to 6.5 g./ft. preferably inrange from 1.8 to 5.6 g./ft.

Any hydrophilic colloid silver halide emulsions containing silverbromide, silver iodide, silver chloride, silver bromoiodide, silverchlorobromide, silver chlorobromoiodide, etc., well known inblack-and-white and color photography are used advantageously in myelements. The silver halide emulsion layers for my color elementsadvantageously contain color-forming couplers or are of the type thatare color developed with color developer solutions containing theappropriate couplers.

My hydrophilic colloids having dispersed in them my rigid solution ofbrightening agent, are coated in photographic elements wherever anultraviolet-absorbing brightened is needed, e.g., in, over, or under alight-sensitive layer coated on any of the above supports, between twoor more light-sensitive layers on any of the above supports, in a layercontaining a reflection pigment such as are described above, etc. Aparticularly advantageous utility for my brightener dispersions is inphotographic print material, and in image-receiving elements for diffusion transfer.

The brightening agents dispersed according to my invention aresubstantially more stable to prolonged exposure to light than the samebrightening agents dispersed in solvents outside my invention.

13 The following examples are included for a further understanding of myinvention:

EXAMPLE 1 Solutions are made of 4,4'-bis(5,7-di-t-amylbenzoxazol-2-yl)stilbene in copoly (vinyl acetal) (vinyl 2-carboxybenzoate) (vinylalcohol) (vinyl acetate) 80: 15:3 :2 by weight and copoly (vinylbntyral)(vinyl alcohol) (vinyl acetate) 882923 by weight, each apermanent solvent of my invention using enough of temporary solvent,i.e., ethyl acetate, to produce a liquid solution. Each of the twoliquid solutions prepared are then dispersed in aqueous gelatin; thegelatin is chilled, noodled and the ethyl acetate removed byevaporation, leaving a dispersion of minute rigid particles having anaverage diameter less than .4 micron and containing the4,4'-bis(5,7-di-t-amylbenzoxazol-2-yl)stilbene.dissolved in theindicated permanent solvent. The composition of each of the dispersionsis such that when reconstituted and coated on a support, there is mg. ofthe brightener/R 500 mg. of the permanent solvent/ft. and 500 mg. ofgelatin/ft Coatings are made of each of the dispersions on a transparentsupport.

EXAMPLE 2 Example 1 is repeated using copolybutyl methacrylate) (acrylicacid), 85:15, by weight, copoly(butylmethacrylate) (methacrylic acid)85:15, by weight, and poly- (t-butylmethacrylate), all solvents outsidemy invention in place of the permanent solvents of my invention used inExample 1. The coatings are made so that the coating rates ofbrightener, permanent solvent and gelatin are the same as in Example 1.These coatings are used for controls in Example 3.

EXAMPLE 3 The fresh coatings made in Examples 1 and 2 are compared forbrightener fading caused by exposure to a. SANS (Simulated Average NorthSkylight-500 ft. candle filtered Xenon Fadeometer held at 70 F., 50%RHi1%) test. The brightener fading is monitored by plotting the densityat 380 mm. vs. fading time and interpolating to obtain the half-life (TA2) of the 4,4-bis-(5,7- di-t-amylbenzoxazol-Z-yl)stilbene in each ofthe coatings. The density values used in the plots are uncorrected forby-product absorption, and corrected for stain present from solvent, geland support. The results are summarized with the Tg values for thepermanent solvents used.

TABLE 1 alcohol) (vinyl acetate) 88:928.

The results show up to more than seven times longer half life for thebrightener in my coatings than the same brightener in coatings outsidemy invention.

EXAMPLE 4 Example 1 is repeated using equivalent weights of4-(anaphthotriazol-Z-yl) -4'-octylstilb ene,

4- 5 ,7-di-t-amylbenzothiazol-Z-yl) -4'-(4-octyloxazol- 2-yl) stilbene,4,4'-bis- (5 -octylbenzoxazol-2-yl -m-methylstilb ene, 4,;3-(di-t-amylbenzoxazol-Z-yl styrene, 4,4-bis6-methylsulfonylbenzoxazol-Z-yl stilb ene, 4,4-bis 5 -methoxybenzoxazol-2-y1 stilbene,

1 4 4,4-bis 6-chlorobenzoxazol-2-yl) stilbene, 4,4'-bis(G-docosylbenzoxazol-Z-yl) stilb ene, 4,4-bis(5,7-dit-arnylbenzoxazol-2-y1)3,3 '-dimethyl stilbene, 4,4'-bis(benzoxazol-Z-yl -2,2'-dioctadecylstilbene, 4,4'-bis(benzoxazol-2-yl-2-phenylstilbene, 4,4-bis(5,7-di-t-amylbenzoxazol-Z-yD B, 3-dimethylstilbene, 4- (5 ,7-di-t-amylbenzothiazol-Z-yl-4'-phenylstilbene, 4,4-bis (5-chlorobenzothiazol-2-yl) stilbene,4,4'-bis( 5 ,7-di-t-amylbenzimidazol-Z-yl -stilbene, 4,4-bis6-0ctylbenzoimidazol-Z-yl stilbene, 4,4-bisa-naphthoxazol-2-ylstilb-ene, 4,4'-bis 5,,8-naphthoxazol-2-yl -sti lb ene, u,,8-bis5,7-dioctadecylbenzoxazol-Z-yl) ethylene, 3-phenyl-7-[4-chloro-6'-diethylamino-s-triazinyl- 2) amino] coumarin,7-diethylamino-4-methylcoumarin, 7-[4,6-dichloro-s-triazinyl-(2')ureido] -3- phenylcoumarin, 7-( [4,5-a] naphthotriazol-Z-yl-3-phenylcoumarin, 2,5-bis 5 ,7 -di-t-amylbenzoxazol-Z-yl) thiophene,2,5 -bis (5 ,7-diphenylbenzoxazol-Z-yl) thiophene,2,5-bis(a-naphthimidaZOI-Z-yl thiophene, 1,1-dioxydibenzthiophene,6-ethyldibenzthiophene, S-ethyldib enzfuran, 1 -phenylcarbazole,iiuorene, 9-cyanoanthracene, 9,10-diphenylanthracene,

in place of 4,4'-bis(5,7-di-t-amylbenzoxazol-Z-yl)stilbene. Thebrightening agents in these coatings of dispersions of my invention havevery good stability to prolonged exposure to light.

EXAMPLE 5 Solutions are made of each of the brighteners and polymericsolvents indicated in the table below by dissolving 10 mg. of brightenerin 24 ml. of a 10% ethyl acetate solution of the polymeric solvent. Theresulting solutions are hand-coated on pieces of a transparent filmsupport, the ethyl acetate removed by evaporation, leaving a thin, solidsolution containing between 7.5 and 15 mg./ft. of brightener at a ratioof 1:240 in the polymer. The brightener loss is determined by measuringthe peak U.V. density (at A max. of absorption band) before and afterfour weeks of fading on a SANS (simulated average north skylight)fadeometer at an intensity of 500 ft. candles at 70 F., 50% RH. Theoriginal density at A max. and the density loss from four weeks offading on the SANS fadeometer are listed in the following table:

TABLE II Brightener stability Density loss Original from 4 weeks densitySANS Bnghtener Rigid solvent at A ml:- fading A X (control) 1.35 .48 AY 1. 46 19 B X (control) 0.94 52 B 1. 05 25 O X (control) 0. 93 17 O0.95 .13 D..- X (control) 1.22 .97 D- 1. 21 67 E X (control) 1.00 .94 F.1.07 .74 F X (control) .50 .45 F p .53 .32 G X (control)-.... .53 48 G Y.50 .37 H X (control) .76 .11 H Y 05 1 Gone.

The identity of the brighteners A through I and rigid solvents X and Yare given below:

Brightener A: 4,4-bis (5 ,7-di-t-amylbenzoxazol-Z-yl) stilbene B3-phenyl-7- [4-chloro-6'-diethylamino-s-triaziny1- (2' amino] coumarin2,5-bis(5,7-di-t-amylbenzoxazol-Z-yl)thiophene a-(benzoxazol-2-yl)-4'-cyanostilbene 7-diethylamino-4-methylcoumarin 9-cyanoanthracene9,10-diphenylanthracene 4methyl-3-phenyl-2-oxo-2,4-dihydrofuro[2,3-b]quinoxaline Polymeric solvent X: copoly (butylacrylate) (acrylic acid)60:40 by weight (control Outside invention), Tg=37 C.

Y: copoly (vinyl acetyl) (vinyl Z-carboxybenzoate) (vinyl alcohol)(vinyl acetate) 802151322 by weight, Tg=107 C.

The results show that all the brightening agents used are up to twotimes more stable to the SANS fading when dissolved in my rigid solventthan when dissolved in a rigid solvent outside my invention.

EXAMPLE 6 Solutions are made of each of the brighteners and polymericsolvents indicated in Table III by dissolving 10 mg. of the brightenerin 3 ml. of a 10% ethyl acetate solution of the polymeric solvent. Eachsolution is dispersed in a separate 6 ml. of aqueous bone gel using aconventional dispersing technique. Each dispersion is dried to eliminateethyl acetate, reconstituted and coated on ditferent pieces of atransparent support to give mg./ft. of brightener (density at A max. 0.9to 1.1), 300 mg./ft. of polymeric solvent and 300 mg./ft. of gel on thesupport. The brightener loss is determined by measuring the peak U.V.density (at A max. of absorption band) before and after four weeks offading on a SANS fadeometer using the conditions described in Example 5.The brightening agent loss is indicated by the density loss reported inthe following table:

Brightener A, i.e., 4,4-bis(5,7-di-t-amylbenzoxazol)stilbene and -B,i.e., 3-phenyl-7-[4-chl0ro-6'-diethylamino-striazinyl-(Z)amino]coumarinare from 2 to 3 times more stable in my coatings than in controlcoatings.

EXAMPLE 7 "Example 6 is repeated but using the brightening agents andrigid solvents indicated in Table IV in place of those used in Example6, and coating the reconstituted brightener compositions to give 10mg./ft. of brightening agent, 500 mg./ft. of rigid solvent and 500mg./ft. of gel on the support. The brightening agent loss in thesecoatings from four weeks SANS is indicated by the density loss in thefollowing table:

Density loss Coat- Brightfrom 4 weeks ing ener Rigid solvent SANS 1 AControl (outsideinvention) copoly 74 (butylmethacrylate) (methacrylicacid) 85:15, by weight. 2 A Control (outside invention) poly-(t- 65butylmethacrylate) 3 A Solvent of invention copoly (vinyl 30 butyral)(vinyl alcohol) (vinyl acetate) 88:9:3, by weight. L (2 Control (same asin coating 2, Table IV) 5!] 5 C Solvent of invention used in coating 3,21

Table IV.

16 Brightener A, i.e., 4,4'-bis(5,7-di-t-amylbenzoxazol-Z-yl) stilbeneand Brightener C, i.e., 2,5-bis(5,7-di-t-amylbenzoxazol-2-yl)thiopheneare up to more than two times more stable in my coatings than in thecontrol coatings.

EXAMPLE 8 Example 6 is repeated but using the rigid polymeric solventsand brightening agents indicated in Table V in place of the solvents andbrighteners used in Example 6. The amounts of brightener, rigid solventand gel are adjusted so the coatings made from the reconstituteddispersions contain 10 mg. of brightener, 500 mg. of rigid solvent and500 mg. of gel per square foot of coating. The loss in brightening agentproduced in the coatings by four weeks SANS fading is indicated by thedensity loss data in the following table:

TABLE V Density loss Coat- Brightfrom 4 weeks ing ener Rigid solventSANS 1 A Control (outside invention) (for coat- 69 ings 2 3, and 5)copoly (vinyl formal (vinyl alcohol) (vinyl ace- 2 -2. A Copoly (vinylbutyral) (vinyl alcohol) 27 (vinyl acetate) 88:9:3, M.W. 34-32%,000. 3 ACopoly (vinylbutyral) (vinylalcohol) 28 (vinyl acetate) :17 :3, M.W.till-34,000. 4 -5. A Copoly (vinyl but al) (vinyl alcohol) 29 (vinylacetate) 80:17:25, M.W. 55-60,000. 5 A Copoly (vinylbutyral) (vinylalcohol) 30 (vinyl acetate) 8021921, M.W.

-4 000. 6 A Control (outside invention) for coat- .65

ings 7 and 8 copoly (butyl methacrylate) (methacrylic acid) :15 byweight, Tg 66 C. 7 A Copoly (vinyl butyral) (vinyl alcohol) 29 (vinylacetate) 88:9:3, M.W. 45-55,000. Copoly (vinyl butyral) (vinyl alcohol)27 (vir21glm61cetate) 80:17:13, M.W. Control rigid solvent used incoating 1.; 53 Rigid solvent used in coating 2 0 Rigid solvent used incoating 3 20 Rigid solvent used in coating 4 20 Rigid solvent used incoating 5 I 19 Brightener A, i.e.,4,4'-bis(5,7-di-t-amylbenzoxazol-Z-yl) stilbene and Brightener C, i.e.,2,5-bis(5,7-di-t-amylbenzoxazol-2-yl)thiophene in coatings madeaccording to my invention are up to more than two times more stable thanthe same brighteners in control coatings outside the invention.

EXAMPLE 9 The dispersions of my brightener-solvent solutions in gelatindescribed in Examples 1, 3, 4, 6, 7 and 8 are coated on a baryta-coatedpaper support in place of the transparent support used in the earlierexamples. The brightening agents in these coatings have exceptionallygood stability to prolonged exposure to light.

EXAMPLE 10* The dispersions of my brightener-solvent solutions ingelatin described in Examples 1, 3, 4, 6, 7 and 8 are dispersed intoportions of a baryta coating composition and the resulting compositionscoated on pieces of a paper support. The brightening agents in thesecoatings have exceptionally good stability to prolonged exposure tolight.

EXAMPLE 11 The dispersions of my brightener-solvent solutions in gelatindescribed in Examples 1, 3, 4, 6, 7 and 8 are repeated using equivalentweights of copoly (vinyl acetal) (vinyl 2-carboxybenzoate) (vinylalcohol) (vinyl acetate) 90:5 :3:2 by weight, copoly (vinyl acetal)(vinyl 2-carboxybenzoate) (vinyl alcohol) (vinyl acetate) 70:20:80. byweight, copoly (vinyl butyral) (vinyl alcohol) (vinyl acetate) 80:17z3by weight, m. wt. 3034,000, copoly (vinyl butyral) (vinyl alcohol)(vinyl acetate) 80:17:3, by weight, m. wt. 55-60000, copoly (vinylbutyral) (vinyl alcohol) (vinyl acetate) 80:19:1, by weight, In. wt.38-45,000, copoly (6-methylene-2-phenyl-1,3-dioxalane) (vinyl alcohol)(vinyl acetate) 8011713, by weight, copoly(6-methylene-2-u-naphthyl-1,3-dioxalane) (vinyl alcohol) (vinyl acetate)80:17:3, by weight, copoly (6-methylene-2-methyl 2 propyl-l,3-dioxalane)(vinyl alcohol) (vinyl acetate) 88:9:3, by weight, copoly (G-methylene 2octadecyl-1,3-dioxalane) (vinyl alcohol) (vinyl acetate) 88:9:3, byweight, and copoly (6-methylene-2,4-dimethyl-1,3-dioxalane) (vinylalcohol) (or-methyl vinyl alcohol) (vinyl acetate) (or-methyl vinylacetate) 80:7:7:3:3, by weight, in place of the permanent solvents usedin Examples 1, 3, 4, 6, 7 and 8, and coating the dispersions on piecesof a paper support instead of a transparent support. The brighteningagents in these coatings of my invention have excellent stability toprolonged exposure to the SANS test.

EXAMPLE 12 Paper and baryta coated paper supports are coated With thedispersions of my brightener-solvent solutions described in Examples 1,3, 4, 6, 7,8, and 11 and these coatings are overcoated with an ordinarygelatin-silver chlorobromide emulsion. The dried coatings are given alight image exposure and developed to a silver image with an aqueousalkaline solution containing hydroquinone and p-methylaminophenolfollowed by water washing, fixing in a conventional alkali metalthiosulfate bath, washed and dried. The highlight areas of the printsexhibit a high degree of brightening from the brighteners even afterprolonged exposure to light.

EXAMPLE 13 A piece of photographic paper coated with a gelatin layercontaining a dispersion of 4,4'-bis(5,7di-t-amylbenzoxazol-2-yl)stilbenedissolved in copoly (vinyl butyral) (vinyl alcohol) (vinyl acetate)88:9:3, by weight, In. wt. 3448, 000 and a dispersion of baryta iscoated in succession (over said brightening layer) with (1) an ordinaryblue-sensitive gelatino silver chlorobromide emulsion and a dispersionof a yellow dye-forming coupler of the type described in McCrossen etal., US. Pat. 2,875,057, (2) a gelatin interlayer, (3) a gelatin layercontaining an ordinary green-sensitized gelatino-silver chlorobromideemulsion, a dispersion of a magenta dyeforming coupler, such as, one ofthe couplers described in Loria et al. U.S. Pat. 2,600,788, (4) agelatin layer, (5) a gelatin layer containing an ordinary red-sensitizedgelatino silver chlorobromide emulsion, a dispersion of a cyan dyeforming coupler such as is described in Fierke U.S. Pat. 2,801,171, and(6) a gelatin protective layer. The photographic element is exposed inan intensity scale sensitometer and then color processed as described inExample 1, columns 5 and 6 of Van Campen U.S. Pat. 2,956,879 using 12minutes development in the color developer. The processed color printhas brightened highlights that even after prolonged exposure to lightretain their brightness to a much higher degree than control colorprints made by the same way, excepting that the brightening agent isdispersed as a solution in di-n-butylphthalate.

[EXAMPLE 14 Example 13 is repeated, using equivalent weights of copoly(vinyl 'butyral) (vinyl alcohol) (vinyl acetate) 8011723 by weight, In.wt. 24-28,000, in. wt. 30-34,000, in. wt. 55-60,000, 80: 19:1 111. wt.38-45,000 copoly (vinyl acetal) (vinyl Z-carboxybenzoate) (vinylalcohol) (vinyl acetate) 80: :32 by Weight in place of the rigid solventused in Example 13. Results similar to those in Example 13 are obtained.

EXAMPLE 15 Example 13 is repeated using equivalent weights of thebrightening agents used in Example 4 in place of 4,4- bis(5,7-di-t-amylbenzoxazol-Z-yl) stilbene used in Example 13. Resultssimilar to those in Example 13 are obtained.

My brightening compositions are advantageously used in image-receivingelements that are used to receive diffusion transfer images during thediffusion transfer process. In these processes, a light-sensitivediffusion transfer element containing a light-image exposed silverhalide emulsion is processed with the exposed emulsion layer in contactwith the silver precipitating layer of an imagereceiving element in thepresence of a silver halide developing agent, such as hydroquinone,1-pl1enyl-3-pyrazolidone, p-methylaminophenol, etc.,. a silver halidesolvent or complexing agent, such as an alkali metal thiosulfate,ammonium thiosulfate, an alkali metal thiocyanate, ammoniurnthiocyanate, etc. In a particularly useful process, a thickening agent,such as carboxymethylcellulose, carboxyethylcellulose, etc. is used.During development, undeveloped silver halide forms a complex with thecomplexing agent which diliuses in an imagewise manner to thesilver-precipitating layer on the image-receiving element "Where asilver image is precipitated from the silver halide complex. In anintegral element, a silver halide emulsion coated over a silverprecipitating layer is removed such as by washing, to disclose thetransferred image. In a color diffusion transfer process, animage-exposed light-sensitive silver halide color diffusion transferelement is contacted with the receiving layer of an image-receivingelement in the presence of a developer solution which causes the releaseof a dilfusible dye image that transfers to the mordanted receivinglayer. The desired dye image remains in the receiving layer when thereceiving element is separated from the developed diffusion transferelement. The dlilfusible dye image is formed from an incorporatednon-ditfusible coupler that couples with an imagewise pattern ofoxidized primary aromatic amine color developing agent, produced bydevelopment of light-exposed silver halide. In another system, the dyeimage is formed from incorporated dye developing agents, such ashydroquinone derivatives that contain a chromophore as a substituent;the hydroquinone form of these compounds forms in the alkaline developersolution a diffusible dye while the dye developer that is oxidized tothe quinone form (when it develops light-exposed silver halide tosilver) is insoluble and does not diffuse to the image-receiving layer.

My brightening compositions are advantageously used in image-receivingelements. My image-receiving elements usually comprise a support asdescribed previously that has been coated in succession with (1) abaryta layer containing my brightening composition, and (2) animage-receiving layer for a silver image comprising any of thehydrophilic colloids such as have been described before, containing adispersion of a silver precipitating agent or an image-receiving layerfor a dye image comprising any of the hydrophilic colloids such as havebeen described before, containing a basic mordant for mordanting acidsolubilized dilfusible dyes. Usually it is advantageous to have ahydrophobic resin layer between the baryta layer and the image-receivinglayer. Hydrophobic resins that are advantageously used includepoly(ethylene terephthalate), polyethylene, polypropylene, poly-(3-methylbutene-1), poly(octene-l), poly(decenel), polyamides,polyacetate, polycarbonates, cellulose, triacetate, cellulose acetatebutyrate, ethyl cellulose, etc.; preferably the hydrophobic resin layeris treated with corona discharge techniques just prior to coating thefirst hydrophilic colloid layer over the resin as described in U.S.patents such as 3,220,842, 2,864,755, 2,864,756, etc. In one alternativestructure, the baryta layer and brightening composition layers arecoated separately between the support and image-receiving layer. Instill another alternative structure, the image-receiving elementcomprises a support coated with a hydrophilic colloid layer containingboth my brightening composition and a silver precipitating agent ormordant (for a dye transfer image).

Any suitable silver precipitant from the prior art is advantageouslyused in my receiving layer. As examples of suitable silver precipitatingagents and of image-receiving elements containing such silverprecipitating agents, reference may be made to U.S. Pat. Nos. 2,698,-237, 2,698,238 and 2,698,245, 2,774,667, 2,823,122, 3,396,018 and3,369,901. The noble metals silver, gold, platinum, etc. in thecolloidal form are particularly useful.

Noble metal nuclei are particularly active and useful when formed byreducing a noble metal salt using a borohydride or hypophosphite in thepresence of a colloid as described in Rasch, U.S. Patent applicationSer. No. 796,552, filed Feb. 4, 1969. The metal nuclei are prepared inthe presence of a proteinaceous colloid such as gelatin and coated onthe receiving element. The coating composition generally contains notonly nuclei, but also reaction products which are obtained from reducingthe metal salt.

The amount of colloid used in preparing the above active noble metalnuclei can be varied depending upon the particular colloid, reducingagent, ratio of proportions, etc. Typically, about 0.5% to about 20%, byweight, based on the total reaction mixture of colloid is used,preferably from about 1% to about 10%.

In a particularly useful embodiment, 30 to 80 ,ug/ft. of the activenoble metal nuclei in 80 mg. of colloid (solids basis) is coated persquare foot of support. The colloid binder is advantageously coated in arange of about 5 to about 500 mg./ft. Suitable concentrations on thereceiving sheets of active noble metal nuclei as disclosed above can beabout 1 to about 200 ,ug./ft. Other silver precipitants can be coated ina concentration of up to 5 mg./ft.

Any of the prior art mordants that have a charge oppsite to the chargeof the dye being transferred are used to advantage in my image-receivingelements for dye transfer images. Since most of the useful photographicimage-transfer dyes have acidic solubilizing groups, basic or cationicmordants are generally used. Typical mordants are organic quaternaryphosphonium salts, organic ternary sulfonium salts and organicquaternary ammonium salts. Suitable mordants include polymers of aminoguanidine derivatives of vinyl methyl ketone described in Minsk, U.S.Pat. 2,882,156. Other suitable mordants include the 2-vinyl pyridinepolymer metho-p-toluene sulfonate, poly 4-vinyl-pyridine, thorium saltsand similar compounds described in Sprague et al., U.S. Pat. 2,484,430.

A particularly useful class of mordanting compositions is disclosed inBush, U.S. Pat. 3,271,147. Basic or cationic, nonpolymeric mordantcompounds of Bush include quaternary ammonium and phosphonium, andternary sulfonic composition in which there is linked to the N, P or Sonium atom at least one hydrophobic ballast group, such as long-chainalkyl or substituted alkyl groups. The onium atom can be part of anopen-chain or of a heterocyclic ring and there can be more than oneonium ring in the molecule. When referring to the nonpolymeric nature ofthe mordant compounds of such mordanting compositions, I mean that thecationic or the basic mordant does not have regularly occurring unitscontaining the cationic group beyond the dimer structures. However, theballast group attached to the quaternary or ternary atom of the cationgroup can contain repeating groups such as tetraethoxy, polymethylene,etc.

EXAMPLE 16 A silver image transfer receiving element is made by coatinga paper support in succession with (1) aqueous gelatin having dispersedin it (a) a solution of 4,4'-bis- (5,7-di-t-amylbenzoxazol-Z-yl)stilbenein copoly (vinyl acetal) (vinyl 2 carboxybenzoate) (vinyl alcohol)(vinyl acetate) 80:15 :3:2, by weight prepared for coating as describedin Example 1 and (b) baryta, (2) a layer of polyethylene that is treatedby corona discharge (as de- 20 scribed in U.S. patents, such as3,220,842, 2,864,755, 2,864,756, etc.) just prior to coating with (3) alayer of aqueous gelatin containing about 10% by weight of a dispersionof colloidal silver so that about ,ug. of colloidal silver are coatedper square foot.

EXAMPLE 17 A silver miage transfer receiving element is made by coatinga paper support in succession with (1) a layer of an aqueous gelatinbaryta coating composition, (2) a layer of aqueous gelatin havingdispersed in it a solution of 4,4'-bis(5,7-di-t-amylbenzoxazol)stilbenein copoly (vinyl butyral) (vinyl alcohol) (vinyl acetate) 88:9:3 byweight, prepared for coating and coated as described in Example 7, and(3) a layer of aqueous gelatin containing about 10% by weight of adispersion of colloidal silver so that about 150 ,ug. of colloidalsilver are coated per square foot.

EXAMPLE 18 A silver image transfer receiving element is made by coatinga paper support with a layer of aqueous gelatin having dispersed in it asolution of3-phenyl-7-[4-chloro-6'-diethylamino-s-triazinyl-(2')-amino]coumarin incopoly (vinyl butyral) (vinyl alcohol) (vinyl acetate) 88:9:3 by weightprepared for coating as described in Example 7 (but using the immediatebrightening agent in place of those used in Example 7), but also havingdispersed in it colloidal silver and coating so that there is 10 mg. ofthe brightener, 500 mg. of rigid solvent, 150 ,ug. of colloidal silverand 500mg. of gelatin per square foot.

EXAMPLE 19 A separate piece of light image exposed photographic elementcomprising a film support coated with a negative speed gelatin silverbromoiodide emulsion is contacted in the dark with the colloidal silvercontaining layer of a piece of the image receiving element made in eachof Example 16, 17 and 18 in the presence of a conventional silver imagetransfer developer composition comprising water, alkali, hydroquinone,sodium thiosulfate, etc. After development is completed, the imagereceiving element is stripped from the processed photographic element.The highlight portions of the silver image reproductions in each of thereceiving sheets are substantially brightened by my brightener.Comparisons made with similar prints made using identicalimage-receiving elements, excepting that the brightener is dissolved incopoly (vinyl formal) (vinyl alcohol) (vinyl acetate) instead of thepolymeric solvents used in Examples 16, 17 and 18, show that my printsretain the brightener for substantially longer periods of exposure tolight.

EXAMPLE 20 A dye image transfer receiving element is made like thereceiving element in Example 16 excepting that the layer 3 is replacedby a layer of aqueous gelatin containing the mordant cetyl trimethylammonium bromide so that 150 mg. of mordant and 300 mg. of gelatin arecoated per square foot.

EXAMPLE 21 A dye image transfer receiving element is made like thereceiving element in Example 17 excepting that the layer 3 is replacedby a layer of aqueous gelatin containing the mordant cetyl trimethylammonium bromide so that 150 mg. of mordant and 300 mg. of gelatin arecoated per square foot.

EXAMPLE 22 A dye transfer receiving element is made like the receivingelement in Example 18 excepting that the colloidal silver is replaced bythe mordant cetyl trimethyl ammonium bromide so that 150 mg. of mordantare coated per square foot.

21 EXAMPLE 23 Separate pieces of a color film described in Example 1 ofBarr et al., U.S. Pat. 3,227,551, are exposed to an original coloredimage and contacted with the mordant containing layer of the receivingelements made in Examples 20, 21 and 22 in the presence of a developersolution as described in Example 1 of U.S. Pat. 3,227,551. After 5minutes development at 85 F., the receiving elements with their colorpositive reproductions of the original image are stripped from theprocessed color film. The highlight areas of these color prints (in thereceiving elements) are brightened by my brightener composition.Comparisons made with color prints produced exactly the same way, exceptthat the brightening agent in the dye image-receiving elements isdissolved in di-n-butylphthalate, show that the brightener in colorprints made according to my invention is substantially more stable toprolonged exposure to light than color prints outside my invention.

Brightening agents of Formula II in which G and G' each represent C andX and X each represent 0, S or NR are advantageously synthesized byreacting one mole of a compound of Formula XII with two moles of acompound of Formula XIII, XIV, V or VI.

0 R4 Rf] R9 Ra R7 0 @k =i@ LE1 R2 Jm-l R10 LRB 6-Jp-l (or correspondingdicarbox lic acid) (XIII) R11 Rm- NH:

(XIV) 11 R; l XH NH2 Rrr- R 4- Rm R1 R1i ur- NH! Rio (X 12 liln R13 XQHR 4 NH:

wherein R through R m and p are as defined previously and X represents0, S or NR in which R is as defined previously. Many of thebi's(benzoxazol-2-yl)stilbenes used according to my invention aredescribed in U.S. Pat. 3,260,715 and in U.S. Pat. 3,322,680. The4,4'-bis(benzothiazol 2 yl)stilbenes, 4,4 bis(naphthothiazol-2-yl)stilbenes, the 4,4 bis(benzimidazol 2 yl)stilbenes and 4,4bis(naphthimidazol 2 yl)stilbenes are advantageously prepared by methodsanalagous to those shown for preparing the4,4-bis(benzoxazol-Z-yl)stilbenes.

Unsymmetrical substituted stilbenes of Formula II in which X and X are0, S or NR are advantageously synthesized by reacting the di(acidchloride) of stilbene with an excess of phenol in alkaline solution toproduce the diester. 4-Carboxy-4'-phenoxycarbonyl stilbene is preparedby partial hydrolysis of the diester, then the free carboxylic acidgroup is transformed into the acid chloride by treatment with thionylchloride. The acid chloride is then reacted with the appropriatecompound of Formula XII, XIII, XIV, XV or XVI. The remaining phenylester group is then hydrolyzed, to the carboxy group, which is convertedto the acid chloride and then this intermediate reacted with theappropriate compound of Formula XII, XIII, XIV, XV or XVI to make thedesired unsymmetrical stilbene.

Brighteners of Formula II in which X, X, G and G are N, and m and p are2, are advantageously made by diazotizing 4,4'-diaminostilbene, thencoupling each mole of the 4,4-diazotized stilbene with two moles ofo-nitroaniline to make the corresponding 4,4-bis(2-nitrophenylazo)stilbene which is then reduced with zinc dust and sodium hydroxide inalcohol to produce the 4,4'-bis- (benzotriazol-Z-yl) stilbene. Thesymmetrical as well as the unsymmetrical stilbene brighteners withbenzotriazol- 2-yl groups are known in the prior art. The brightener4-(u-naphthotriazol-2-y1) 4' octylstilbene is described generically byU.S. Pat. 3,406,070.

Brighteners of Formula II in which X and X are CR groups and G and G arenitrogen atoms, and m and p are 2, are advantageously prepared bytreating a compound of the formula:

(XVIII) Rn wherein R, R ,R12 R and R are as defined previously, withpowdered zinc to produce the corresponding stilbene compound followed bytreatment with tin and hydrochloric acid to produce the desiredbrightener compound.

The brightener 4(5,7-di-t-amylbenzothiazol-Z-yl)-4'-(4-octyloxazol-2-yl) stilbene is advantageously prepared by reacting4-amido-4'-(5,7-di-t-amylbenzothiazol-Z-yl) stilbene with a-bromomethyloctyl ketone, then reacting the reaction product with NH then removingwater. The brightener 4-(5,7-di-t-amylbenzothiazol 2 yl)-4'-(4-octylimidazol-2-yl) stilbene is advantageously prepared by reacting4-amido-4'-(5,7-di-t-amylbenzothiazol- 2-yl) stilbene witha-bromometh'yl octylketone, reacting the reaction product with NHremoving one mole of water, treating again with NI-I and again removingone mole of water.

The coumarins, thiophenes (including the dibenzthiophenes and1,l-dioxydibenzthiophenes), furans (and dibenzfurans), anthracenes,pyrazolines, fluorenes, carbazoles, 1,8-naphthalic acid imides,2-oxo-2,4-dihydrofuro- [2,3-b]quinoxalines are known in the art andthose not specifically described are readily prepared by well-knownmethods.

The polymers used to advantage as solvents according to my invention areprepared by methods well known in the polymer art. Many of the polymersare available commercially.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

I claim:

1. A brightening composition comprising a hydrophilic colloid containinga dispersion of a solid solution of (A) at least one oil-solublebrightening agent selected from the class consisting of a vinylenebrightening agent, a coumarin, a thiophene, a furan, an anthracene, apyrazoline, a fluorene, a carbazole, a 1,8-naphthalic acid imide and a2-oXo-2,4-dihydrofuro[2,3-b]quinoxaline brightening agent dissolved in(B) a rigid, essentially hydrophobic organic solvent having a glasstransition temperature above about 25 C., said solvent being a polymercontaining recurring units of:

wherein E and E each represent a member selected from the classconsisting of hydrogen, an alkyl group having from 1 to 20 carbon atoms,and an aryl group, such that at least one of E and E is a substituentother than hydrogen; E represents a member selected from the classconsisting of hydrogen, alkyl and COE E represents a group selected fromthe class consisting of an alkyl group, and an aryl group; and xrepresents a number in the range of from about 0.4 to 1.0, substantiallyall of said brightening agent in said hydrophilic colloid beingdispersed in said rigid solvent.

.2. T he brightening composition of claim 1 in which said organicsolvent is copoly(vinyl acetyl) (vinyl Z-carboxybenzoate) (vinylalcohol) (vinyl acetate) 80:15:32, by weight.

.3. The brightening composition of claim 1 in which said organic solventis copoly(vinyl butyral) (vinyl alcohol) (vinyl acetate) 882923, byweight.

4. A brightening composition of claim 1 containing dispersed baryta.

5. A brightening composition of claim 1 containing a dispersed silverprecipitating agent.

24 6. The brightening composition of claim 1 in which said hydrophiliccolloid is gelatin.

References Cited UNITED STATES PATENTS 2,193,035 3/1940 Matthews et al.260-73 LX 2,508,295 5/ 1950' Reckmeyer 9684 X 2,410,225 10/1946 Macht etal. 260 73 L 2,582,357 1/1952 Sargent 252301.2W 3,020,155 2/ 1962 Yackelet al. 9696 X 3,178,445 4/1965 Maeder 252301.2 W 3,203,956 8/1965 Orelup252301.2 W X 3,351,591 11/1967 Siegrist et al. 2523012 W 3,359,10212/1967 Pattijn et al 9682 X 3,413,233 11/1968 Siegrist et al. 252301.2W3,558,316 1/1971 Keberle et al. 9682 2,828,204 3/1958 Taylor et al.96114 3,260,715 7/ 1966 Saunders 252301.2 3,269,840 8/1966 Pattyn et a1.252301.2 3,406,070 10/1968 Oetiker et al. 96114 3,449,257 6/1969 Tuiteet al. 252301.2 3,518,088 6/1970 Dunn et al. 96--76 FOREIGN PATENTS1,122,643 8/ 1968 Great Britain.

571,662 9/ 1945 Great Britain 260-73 L OTHER REFERENCES Sehildknecht, C.F., Vinyl and Related Polymers, Wiley, New York (1959), pp. 333, 334,338-341, 350-352 and 363 relied on.

Yarsley, V. E., et al., Cellulose Plastics, London, Ililfe Books, Ltd.(1964), pp. 109, 115, 117 and 118 relied on.

ROBERT F. BURNETT, Primary Examiner J. C. GIL, Assistant Examiner U.S.Cl. X.R.

